<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>回调函数</title>
</head>
<body>

    </body>
<script>s
    function a (fn){
        setTimeout(()=>{
            let sum = 10
            fn(sum)
        },1000)
    }

    a((arr)=>{
            console.log(arr);
    })

    //简化抽离
    function b(params){
        console.log(params);
    }
    a(b)

</script>   
</html>